Telephone system



Sept. '6, 1927.

1,641,449 H, w. ONEILL TELEPHONE SYSTEM Filed Dec. 1925 Patented Sept. 6, 1927.

UNITED STATES 1,641,449 PATENT OFFICE.

HENRY W. ONEILL. OF ELMHURST, YORK, ASSIGNOR T0 BELL TELEPHONE LAB- ORATORIES, INCORYOR-ATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed December This invention relates to telephone systems and particularly to improvements in methods and means for handling calls over toll and long distance lines.

In terminating such lines, it is usually desired that provision be made for handling tra'flic at different switchboards or positions. Certain positions provide for handling incoming ing calls, others for making through con nections, while special or delayed calls may be handled at certain other positions. Heretofore, all calls were received at inward positions, and such calls as were not to be handled at these positions were transferred to other positions, dependin upon the type of connection desired. In making such transfers, resort is usually nad to local trunks or to signalling circuits local to the toll ofiice or switchboards.

It is the principal object of this invention to provide an improved method and system for more reliably and more economically handling telephone traific of this general nature.

In attaining the above and other objects of this invention, the arrangement of devices and circuits is such that when a call is originated, alternating currents at chosen frequencies will be automatically transmitted over the line for the selection and energization of a line signal at a particular group of positions at a distant toll center. Under this selective system, the attention of an originating and a completing operator only is required, and a saving in line and operating time is thereby eifccted, that is, all transfer operations heretofore required are eliminated.

In carrying out the present invention, a line circuit is connectively accessible to link circuits at a plurality of points within each exchange center. In originating a call, alternating currents over a so-called sleeve conductor which is local to an exchange equipment, el'fect frequency selection of currents which become effective through a sig nal transmitter of a link circuit by way of a line, to energize one of a plurality of signals. This signal thereby selectively calls a particular group of positions or a particular station at a distant exchange point. Each link circuit is also provided with a signal so coordinated with the line equipment that when a connection is made, this signal is calls, others for handling outgo- 19, 1925. Serial No. 76,358.

universally controlled irrespective of the frequency of arriving signalling currents.

This invention is diagrammatically illustrated in the accompanying drawing in which Fig; 1 shows the terminating equipment at one end of a line and portions of a cord circuit arranged in accordance with this invention, while Fig. 2 shows a modified form of the cord circuit portions of Fig. 1.

In the drawing, A indicates such portions of a cord circuit as may be necessary for a clear understanding of this system; B indicates equipment that may be common to a plurality of cord circuit; C indicates a plurality of sources of alternating current of different frequencies that may be common to the equipment B, while D indicates terminating equipment of a line circuit E. The latter equipment comprises jacks 2, 3, 4 and 5, and corresponding line signals 12, 13, 14. and 15, local circuit relays 7 and 11, line relays 25, 26, 4.7, 28 and transformers 3O, 31 and 32 connected in the sleeve conductors of the jacks 3, 4 and 5, respectively.

For convenience of description, let it now be assumed that a duplicate equipment of that shown in. the drawing is present at the distant end of this line circuit E, so arranged that so-called two-way service may be carried out over this line, and so arranged that the line. signals 12 to 15, may be present at each switchboard or group of positions,

while multiples of the respectively associated jacks will be present to render equivalent or corresponding jacks accessible at each of the several position groups.

Let it now be assumed that it is desired to call and extend a connection to a group of positions, corresponding to jack 2 and signal 12. To accomplish this an operator may insert a plug 1 of the cord circuit A into the jack 2, thereby completing a local circuit from grounded battery, winding of relay 6, sleeve terminals of plug 1 and jack 2, winding of relay 7 to ground. This causes the operation of relay 6, which completes the tip conductor of the cord at its upper armature and front contact. The above circuit also causes the operation of relay 7, which in operating its outer lower armature removes the battery shunt from the winding of relay 11. The resistance of the winding of the relay 11 is such as to preventthe operation of any of the lamps 12, 13, 14 and 15 on the operation of any of the combinations of the relays 25, 26, 27 and 28 as will hereinafter be described.

The calling operator now actuates her ringing key 10 to cause the lighting of a lamp corresponding to lamp 12 at the desired positionat the exchange in which the opposite end of trunk E terminates. On the operation .of this key, alternating currents from the sources 20 and 21 of different frequencies are transmitted over thetip and ring conductors of trunk l1] and cause the operation of relays corresponding to relays 26 and 25 respectively at the distant end of the trunk. The circuits for these currents are as follows: from ground, through the alternating current source 20, right hand armatures and back contacts of relays 4:4 and 42, through the inner upper closed contacts of key 10, upper armature and front contact of relay 6, tip terminals of plug 1 and jack 2, over the tip conductor of trunk 12 through relays corresponding to relays 25, 26, 2?, and 28 and a condenser corresponding to condenser 29 in series at the distant end of the trunk, back over the ring conductor of the trunk to the originating exchange, ring terminals of jack 2 and plug 1, the lower closed contacts of key 10, right hand armature and back contact of relay 47, through alternating current source 21 to ground. Relays 25, 26, 27 and 28 and the corresponding relays at the distant end are alternating current responsiverelays that respond to different frequencies, and the relay 26 and its corresponding relay at the distant end are of such character as to operate in response only to alternating current from source 20, while relay and its corresponding relay at the distant end are of such character as to operate in response only to alternating current from source 21.

p The operation of the relays corresponding to relays 25 and 26 at the distant end close a circuit through their lower armature and front contacts as follows :battery, lower armature and back contact of the relay corresponding to relay 7, lower armature and front contact of the relay corresponding to relay 26 and through the lower winding of this relay through the lamp corresponding to lamp 12'at the operators position at the distant exchange through the lower winding of the relay corresponding to relay 25 and through the lower armature and front con tact thereof, through the inner armature and backoontact of the relay corresponding to relay 7 to ground. This circuit causes the lighting of'the lamp corresponding to the lamp 12 and the operator at that position will thus be notified that a! connection requiring her attention is desired.

It will be noted that relays 25 and 26 will also operate on the application of currents from sources 20 and 21, but as relay 7 is operated,,no circuit will be completed for lamp 12 at this call originating exchange at this time. The relays corresponding to relays 25 and 26 at the distant exchange are now locked up through their lower windings under control of the relay corresponding to re lay 7.

The positions at the distant exchange are equipped with cord circuits such as A, and the operator at the called. position on noting the lighted condition of the lamp asso ciated with the trunk IE will insert the answering plug of a cord into the corresponding jack. This closesa circuit for the operation of relays corresponding to relays 6 and 7 at that exchange, and on the operation the latter relay the battery at the lower outer armature thereof will be removed. from the locking circuits thereby releasing the relays correspondingto relays 25 and 26 and crmsequently the lamp corresponding to lauiip 1.2 will be extinguished.

The operators at both ends of the trunk lfi may now operate their listening keys such 5;; 52 and the connnrurication of the desired sub-- scrihers number from the operator at A to the operator at the distant exchange may now ta place. distant exchange has completed a connection to the wanted subscriber and conversation between the ailing and the called subscriber has terminated, the operator at either exchange may transmit a signal to the other operator for any supervisory purpose, for

example, a signal to signify that the connection may be taken down.

lift it is assumed that the operator at the distant end actuato s her ringing key current from sourcescorresponding to sources 20 and 21 will be transmitted back over the trunk E to the originating operators posi tion to cause the operation of relays 25 and in the same manner as when current from the sources 20 and 21 was transmitted to the distant exchange as hereinbefore described. In this case, the operation of relays 25 and 26 does not result in the lighting of lamp 12 as relay 7 is operated, but it should be noted that in this case, relay 11 will operate over a circuit as follows: battery, winding of re lay 11., armature and frontcontact of relay 26, lower winding of relay 26 through lamp 12, lower winding of relay 25-, armature and front contact thereof to ground at the upper armature and front contact of relay 7. The operation of relay 11. causes a circuit to be closed as follows: from ground through alternating current source 21, armature and front contact of relay 11, sleeve terminals of jack 2 and plug 1, lower outer normally closed contacts of key 10, winding of alternating current responsive relay 50, lower armature and front contact of relay 6, through battery to ground. Relay 50 responds to current from this alternating current source, and on the operation of this relay a circuit is closed for the lighting of the When the operator at the supervisory lamp 51 as follows: battery, lower armature and front contact of relay 6, winding of relay 50. armature and front contact thereof, through lamp 551 to ground at the upuer closed contacts of talking key 52. Th circuit causes the locking of relay 50 and the lighting of lamp 51 under control. of relay 6. The lighting of this lamp may inticate to the operator at A that the connection is to be taken down or that the operato at the distunt'exchange desire-s to conununicate With the operator at A. When the operator at A finds the lamp 51 lighted, she may operate talking key 52 to connect her telephone set with that of the operator at the i tant exchange or if the signal is to be interpreted as a disconnect signal, she will simply remore plug 1 from jack 2. In either case it is obvious that relay 50 will release and lamp 51 will be extinguished.

If it is decided to extend the connection to a certain dil'lerent position at the distant ex change, the operator at A inserts plug-1 into jack 3. Relays Band 7 are operated in the same manner as before. It Will be noted. that a different combination of frequencies are transmitted in this case and this is accom plished in a different manner from that of the former case. On the insertion of plug 1 into jack 3, operation of relay 7 and actuation of the ringing key 10, a circuit is closed as follows: from ground, through alternating current source 24:, primary winding of repeatin g coilv 30, middle lower armature and front contact. of relay 7 to ground. Current from this source 24 induces through the secondary winding of repeating coil. 30 an alternating current of the same frequency, and a circuit for this induced current may be traced as follows: from ground through the upper winding of repeating coil 40, lower outer closed contacts of key 10, sleeve terminals of p'lug l and. jack 3, secondary winding of repeating coil 30, armature and back c uitact o relay ll. to grmuid. The current through this circuit will induce in the secondary of repeating coil 40 an alternating current of the same frequency. A circuit for this path may be traced from ground through the relay ll. which is designed to respond to eurrt-uits of this frequency only, and through the secondary winding of re peating coil 40 to {,{lOUIlfl- Relay 4:1, in responding. opens the circuit through its armature am. back contact. which it will be noted sl'mnts the winding of relay 42, so that relay 42 will now operate over a circuit as fol ows: battery, arnniture and back contact of relay 4:3, winding of relay 4 2, armature and back contact of relay 4:6, upper outer closed con-- tacts of key 10 to ground. Due to the operation of relay 42 alternating currents will now be transmitted from sources 2% and 21. That is, alternating current from source 21 will.

be transmitted through the armature and back contact of relay 4L7 through. the lower inner closed contacts of key 10 to the ring conductor of trunk E, while alternating current from source 24 will be transmitted through the armature and front contact of relay through the upper inner closed contacts of key 10 to the tip conductor of trunk E.

In this case, therefore, a relay at the distant exchange corresponding to relay 25 will respond to current from source 21 while a relay at the distant exchange corresponding to relay 2? will respond to current from source 24. The operation of these relays closes a circuit for the operation of a lamp corresponding to lamp 123 at the called position at the distant exchange. This circuit may be traced as follows: Battery, the lower outer armature and back contact of a relay corresponding to relay 7, the lower armature and front contact and lower Winding of a relay corresponding to relay 27, a lamp corresponding to lamp 13, lower Winding, armature and front contact of a relay corresponding to relay 25, the upper normal contact and armature of a relay correspond ing to relay 7 to ground. In this case, therefore, by the combined. action of inserting plug 1 into jack 3 and operating key 10, the lamp at the called position at the distant exchange will be lighted. I

In a similar manner another position at the distant exchange may be selected by in sorting plug 1 into jack el. In this case relays 6 and 7 operate as before, and a circuit in this case is completed from alternating current source 23 through the primary winding of repeating coil 31 to the middle armature and front contact of relay 7 to ground. Current from this source which is of a diffel ent frequency than the current from the other sources, will induce in the secondary of repeating coil. 31 a current of the same frequency, and a path for this current may be traced. as follows: 'round, upper winding of repeating coil 10, lowermost closed contacts of key 10, sleeve terminals of plug 1 and jack 4, secondary of repeating coil 31,

armature and back contact of relay 11 to ground. The current through the primary of repeating coil 40 induces a current of the same frequency through the secondary of this repeating coil, and in this case relay l3 will respond as it is designed to respond only to current of this particular frequency. The circuit for the current through the winding of this relay from the secondary of the repeating coil 40 is obvious. Operation of relay {l3 opens the short-circuit around the winding of relay 4% so that this relay will now operate over a circuit as follows: battery, Winding of relay 44, armatures and back contacts of relays 4.1 and 46, uppermost closed contacts of key 10 to ground. Operation of relay 44L permits current from source 23 to be transmitted through its armature and front contact, the armature and back contact of relay 42 to the tip conductor of the trunk, while current from source 21 will be transmitted as hereinbefore traced to the ring conductor of the trunk.

In thiscase a relay at the distant exchange corresponding to relay 25 will be operated in response to current from source 21 and a.

relay corresponding to relay 28 will be operated in response to current from source .3. A circuit for the operation of a lamp corresponding to lamp 14 will be completed and may be traced as follows: Battery, lower armature and back contact of a relay corresponding to relay 7, armature and, front contact and lower winding of a relay corresponding to relay 28 through lamp corre sponding .to lamp 14, lower winding, armature and front contact of a relay correspond ing to relay 25, lower inner armature and back contact of the relay corresponding to relay 7 to ground. It will thus be clear that When the operator at A inserts the plug 1 into the jack 4 and operates the ringing key 10, current from sources 21 and 23 will be transmitted over the trunk E to energize a lamp at a corresponding position at the distant exchange.

, To light a. lamp at a fourth position the operator at A may insert plug 1 into jack 5. In this case, the operation of relay 7 and the operation of key 10. causes the transmission of currents from sources 20 and 24 as follows: On the operation-of relay 7 a circuit will be closed from source 21, through the primary of repeating coil 32, middle armature and front contact of relay 7 to ground. Current from this source will induce a current of the same frequency in the secondary of repeating coil 32 and a circuit for this induced-current may be traced as follows: from ground through the primary of repeating coil 40, lower outer closed contacts of key 10, sleeve terminalsof plug 1 and jack 5, secondary of repeating coil 32, armature and back contact of relay 11 to ground. This current through the primary of repeating coil 40 induces a current of the same frequency through the secondary of this coil, and in this case, relay 46 will be the relay responding to the current of this frequency. Relay 46 in operating removes the shunt around the winding of relay 47 so that this relay will now operate over a circuit that may be traced from ground, armatures and back contacts of relays 41 and 43, winding of relay 47, upper outer closed contacts of key 10 to ground. It will be noted then that on the operation of relay 47 current from source 24 will be transmitted through the armature and front contact of relay 47 to the ring conductor of trunk E while cur rent from source 20 will be transmitted through the armature and back contact of relays 44 and 42 to the tip conductor of: trunk E.

In this case the relay corresponding to relay 26 at the distant exchange will respond to current from source 20, While the relay corresponding to relay 27 will respond to current from source 24. A circuit Will thereby he completed for the operation of a lamp corresponding to lamp 15 as follows: Battery, lower outer armature and back contact of the relay corresponding to relay 7 armature, front contact and lower winding of relay 26, and. from this battery through the armature, front contact and lower winding of the relay corresponding to relay 27 in parallel, through the resistances corresponding to resistances 34, through a lamp correspondingto lamp 15, lower armature and back contact of the relay corresponding to relay 25, through the lower inner armature and back contact of the relay corresponding to relay 7 to ground. The lighting of the lamp corresponding to lamp 15 at the night operators position will thus result from the combined operation on the part of the operator at A of insertion of plug 1 into pick 5 and the actuation of key 10.

it is evident from the above descrlption that an e; ;ceedingly simple arrangement has b en provided by this invention for selecting d iili'crcut positions at a distant exchange over ch a connection may be extended, that is,

'1. all that the operator at the call originating e. :ch:-inge has to do is to select a jack corresponding to the position desired at the distant end, insert the plug of a cord circuit into this jack and operate her ringing key. it is also evident that by this arrangement calls; may be transmitted and received in both directions over the trunk E and that a l ter a connection has been established supervisory operations may be performed by sim 1 l o aeratin the rin in he in the .1 m e p a usual. manner.

The modification shown in Fig. 2 is identical with the disclosure of the invention in Fig. 1 with the e eption that in place of the alternating current sources 21, 23 and 24 alternating current source of the vibratory relay type have been substituted and arranged to supply currents of different frequencies to the cord and trunk circuits through repeating coils such as 60, 61, 63 and 64. These vibratory relays may receive current for operationonly when a plug is inserted in a jack of a trunk such as E and when the key 10 is operated or when relay 11 is operated. Relay 11 is the same as relay 11 except that a special armature and a contact to ground is provided. A relay 65 is therefore operated each timekey 10 or relay 11 is operated to supply a ground connection for the vibratory relays 66, 67, 68 and 69, and. also for the operation of relays 42, 44 and 47 as hereinbefore described. To

(ill

trace one of these circuits, for example, the circuit forvlbratory relay 66, when relay 1S operated, current will be supplied from battery, 'n'ilnary winding of repeating coil 60, through the windings of tlietwo coils of relay 66 in series to ground at the armature and front contact of relay 65. The operation of relay (36 in response to this current will cause its armature to be operated towards tlu i it and thus short-circuit its own wind ings. In this manner, relay 66 is alternately opa'aled and released, and consequently an alternating current is induced in the second ary winding of repeating coil 60 corresponding in frequency to the frequency of the operation and release of relay 66. These vibratory relays are therefore designed to cause alternating currents of different frequencies to be supplied through the repeating coils 60, 61, 63 and 64 respectively for use in selecting various positions at the dis tant exchange.

hat is claimed is:

1. In a signaling system, line circuits, a'

cord circuit and a signaling key therefor, means for connecting said cord circuit to said lines, a plurality of sources of current of different frequencies, a plurality of tuned relays, a plurality of transformers for each said line circuit, and circuits controlled by said key for applying current from said sources by way of the transformer of a connection to select certain of said tuneda'elays, and relays controlled by said certain tuned relay for selectively applying energy at pre determined frequencies from said sources to said key.

2. In a signaling system, a line having a plurality of connectively accessible points, a plurality ofcurrent sources of different frequencies, a link circuit for extending con nections from said line, a signal transmitter for said link circuit, and frequency con trolled means for selectively rendering currents from said sources effective with said transmitter according to the connective point to which said link circuit may be joined.

3. In a signal transmitting system, a link circuit including a signal transmitter, sources of current having a plurality of frequencies, a line having a plurality of connective points for said link circuit, frequency controlled means for selectively applying said frequencies to said transmitter, and means associated with said connective points to render said transmitter effective to control said frequency controlled means.

4:. In a system of selective signaling, alink circuit and a signal transmitter therefor, a line having a plurality of connective points for joining said link circuit to said line for signaling thereover, sources of current of dilierent frequencies, frequency responsive means for selectively applying current of different frequencies to said transmitter,

and means respectively associated With said connective points to render said transmitter effective to control said frequency responsive means. i

5. In a sign l receiving tern, a line having a plural t y of crmnectively accessible points, a line signal correspon ding with each of said points, frequency controlled relays sclcctiv y r iponsivc in pairs for individually cmitrolliug a corresponding signal, a link circuit for eslaliiliiishing connections at said points, a signal for said link circuit, and means re pensive to the connection of said link circuit at any connective point for disabling said line signals while enabling response of the signal of said link circuit in response to any selected. combination of said frequency controlled relays.

6. In a system for signaling by means of currents at differei'it frequencies, line circuits, a signal transmitter, means for connecting said transmitter to said lines, sources of al ternating currents at a plurality of frequencies, and frequency controlled means rendered effective by the connection of the trai'ismitter to a line for selectively controlling the association of current frequencies with said transmitter.

7. In a signal transn'iitting system, a plurality of normally inert vibrators for producing alternating currents at different frequencies, line circuits, a signal transmitter, means for connecting said transmitter to said. lines, frequency selecting circuits prepared under a connection between said transnutter and line circuit, and means under control of said transmitter to energize the virators for supplying said transmitter with signaling currents.

8. In a telephone exchange system, line circuits comprising main conductors terminated in respective exchanges, an additional conductor associated. with the line conductors in said exchanges, a plurality of signals for each line, sources of alternating currents of different frequencies, transmitting means for applying permutations of said frequencies over said lines to selectively control said signals, and means selectively responsive to energy from said sources by way of the additional conductors for automatically selecting predetermined frequencies from said sources for said transmitting means.

9. In a telephone system, two conductor line circuits each having a third conductor individual thereto at each end thereof, link circuits provided with three conductors for extending connections from the three conductors of said terminating line circuits, signal transmitting means for each link circuit, a plurality of signals for each line at each exchange equipment, sources of current at a plurality of frequencies, and means for applying c rrents from said sources over the third conductor of one exchange equipment Ill for automatically energizing said transmitting means with current at frequencies to predetermine'dly select one of said signals of a line at a distant exchange equipment.

10. In a telephone system, a line circuit, exchange equipment comprising connective points servedby main and local conductors for terminating said line, link circuits for inclusion with said connective points, a signal receiving system for said main conductors, sources of direct current, sources of alternating current of different frequencies, electro-responsive means controlled by the direct current over said local conductor for predeterminedly alfecting said signal receiving system, a signal transmitter for said link circuits, and electro-responsive means controlled by alternating current superimposed over said local conductor for selectively energizing said signal transmitter from said sources of alternating currents.

11. In a telephone system, exchange equip ment including a pair of conductors for-terminating a line, an additional conductor local to said exchange equipment, signal receiving means for said pair of conductors, 'a link circuit for inclusion with said pair and said additional conductor, a signal receiving system for said link circuit, means for applying direct current over said additional conductor for controlling the receiving system of said pair, and means for superimposing alternating current over said additional conductor for controlling the signal receiving system of said link circuit.

12. In a telephone system, a trunk line havinga corresponding plurality of connecting points at each end thereof, a signal individual to each connecting point at each end thereof, tuned relays for actuating said signals at each end thereof, a cord circuit, a signal transmitter associated therewith comprising a plurality of sources of alternating currents and means in said cord circuit selectively responsive to the particular connecting point of said trunk line with which said cord circuit is temporarily associated for 7 switching into operative relation with said signal transmitter, certain of said sources of alternating current to actuate a signal at the distant end of said trunk corresponding to the particular connecting point with which said cord circuit is connected.

In witness whereof, I hereunto subscribe my name this 16th day of December, A. D. 1925.

HENRY W. ONEILL. 

